Some Albian (Cretaceous) asteroids (Echinodermata) from Texas and their paleobiological implications

Abstract

An asteroid fauna is described from the Albian (Cretaceous) interval of the Washita Group of central Texas. New genera and species areAlkaidia sumralli, (Benthopectinidae),Capellia mauricei(Goniasteridae), andBetelgeusia reidi(Radiasteridae). Additional new genera areFomalhautia(Goniasteridae), andDenebiaandAltairia(Ophidiasteridae).Crateraster texensis(Goniasteridae), new combination, is similar to the European type species,C. quinqueloba.An unnamed species ofCraterasterand an unassigned goniasterid are also present. All Washita genera are extinct, but all belong to extant families. The fauna is largely distinct from that of the somewhat younger European Cretaceous chalk.The Radiasteridae (e.g.,Betelgeusia) is inferred to hold a basal position in the Paxillosida;Betelgeusiaextends the range of the family back to the Cretaceous, closer to the diversification of the living asteroid orders. Asteroids capable of burying themselves in sediment (and only self-buriers) share some form of channelization for the passage of water currents between the primary ossicles of the body surface. Channels inBetelgeusiaindicate semi-infaunal habits similar to those of livingAstropectenandLuidia. Betelgeusiarepresents the third semi-infaunal paxillosidan family now known from the Cretaceous, although none are known from older rocks, suggesting a broadening of the asteroid adaptive zone during the Cretaceous. The Goniasteridae, Radiasteridae, and Benthopectinidae are less important in shelf settings today than they appear to have been during Washita deposition, whereas the Astropectinidae, Luidiidae, and the Echinasteridae are absent from the Washita although they are common today in similar settings.